This invention is a portable drywall joint compound pump station that pumps joint compound into drywall finishing tools and facilitates cleanup at drywall construction sites.
Drywall has become a dominant material in the construction of building interiors. In particular, building interiors generally have vertical stud walls that support pre-formed drywall panels attached to the stud walls. Joints between the adjacent drywall panels are taped and finished with joint compound before painting or wallpapering. Many drywall finishing tools have been developed over the years to facilitate taping and finishing with joint compound.
One type of drywall finishing tool is disclosed in U.S. Pat. No. 2,815,142, issuing on Dec. 3, 1957. This tool mechanically applies tape and, contemporaneously, a first coat of joint compound. This mechanical tool includes a reservoir for joint compound that needs to be filled before applying the joint compound to the drywall surface. After the tape and the first coat of joint compound have been applied over the joint, a second and sometimes even a third coat of joint compound are applied. The second and third coats are typically applied using finishing tools such as a flat box or a corner angle finishing tool. Conventional flat boxes and comer angle finishing tools also need to be filled with the joint compound.
A pneumatic apparatus for applying joint compound is disclosed in Denkins U.S. Pat. No. 5,863,146, issuing on Jan. 26, 1999. This tool also needs to be filled with joint compound before applying the joint compound to the joint between adjacent panels of drywall. The Denkins apparatus is powered by compressed air that can be easily metered to effectively control the application of joint compound. Several finishing attachments, such as heads for flat joints and corners, are removably attached to the pneumatic tool.
When working with drywall finishing tools, substantial amounts of time are spent mixing joint compound, filling application tools with joint compound, and cleaning the tools. U.S. Pat. No. 5,878,925, entitled xe2x80x9cDrywall Joint Compound Pump Workstation,xe2x80x9d by Jeffrey L. Denkins and Steven J. Mondlock, issuing on Mar. 9, 1999, and assigned to the assignee of the present application, discloses a drywall joint compound pump workstation that is designed to accommodate these needs, as well as other needs present at drywall construction work sites. The workstation disclosed in the Denkins et al. ""925 patent effectively mixes and pumps joint compound for drywall finishing tools. The pump workstation has a series of quickly interchangeable attachments and is extremely versatile. It is also designed to facilitate rinsing and cleaning of the workstation and drywall finishing tools at the work site. In its commercial embodiment, the pump workstation includes a rather large supply reservoir having an open top and a closed bottom for mixing and holding a supply of joint compound. A gravity fed pump is attached to the bottom of the supply reservoir. A transport tube is connected to the pump, and an outlet of the transport tube is positioned in the vicinity of the open top of the supply reservoir. The top of the transport tube is preferably provided with a quick-disconnect fitting so that one of several attachments can be attached to the outlet of the transport tube to facilitate the task at hand. For example, a gooseneck attachment is attached to the transport tube in order to mix and recirculate joint compound from the supply reservoir through the pump and the transport tube back into the supply reservoir. Various filling adapters are also provided at the top of the transport tube in order to fill various drywall tools, such as the mechanical tool of the type disclosed in U.S. Pat. No. 2,815,142, the pneumatic joint compound application tool as disclosed in Denkins et al. U.S. Pat. No. 5,863,146; or other tools such as flat boxes. In addition, a threaded nipple attachment is provided along with a water hose to facilitate on-site rinsing and cleaning.
In order to facilitate portability of the aforementioned workstation, the workstation is mounted on a conventional wheeled hand truck. The pump is mounted to the base of the hand truck and the supply reservoir is mounted directly above the pump so that both the pump and the supply reservoir are balanced on the hand truck. The pump is preferably a pneumatic pump that is powered by compressed air. The availability of a compressed air supply at the drywall work site is commonplace.
While the drywall joint compound pump workstation disclosed in Denkins et al. U.S. Pat. No. 5,878,925 has been commercially successful, some drywall workers feel that the station may be too expensive or too bulky for their needs. It is an object of the present invention to accommodate the needs of these drywall workers with a portable drywall joint compound pump station that is compact, reliable, and durable. The pump station should also able to fill a variety of application tools with joint compound, and facilitate the rinsing and cleaning of tools on-site.
The invention is a portable drywall joint compound pump station that uses a pneumatic pump to pump joint compound from a mud container such as a five gallon bucket or other similar container. The pneumatic pump is preferably a double diaphragm pneumatic pump. In order to use the pump station, the drywall joint compound should be pre-mixed in the container. In the preferred embodiment of the invention, the pneumatic pump is mounted to a frame having legs that support the pneumatic pump at a height above the ground such that an inlet for the pump is higher than the typical height for a five-gallon bucket. Alternatively, it may be desirable for the bottom of the legs to mount onto the container itself (see for example FIGS. 15-17).
An intake tube is connected to the pump inlet and extends downward such that the inlet port for the intake tube is positioned close to the bottom of the container when the intake tube is placed within the container (e.g., xc2xdxe2x80x3-xc2xexe2x80x3 above the ground surface). In order to accommodate the suction of a consistent flow of mixed drywall joint compound through the pneumatic pump, it is important that the diameter of the intake tube be sufficiently large to avoid significant restriction of the flow of joint compound through the intake tube into the pump. Preferably, the inside diameter of the intake tube is about two inches. The pump outlet preferably faces in the same direction as the pump inlet, thereby enabling the filling of tools to occur over the open top of the container. This configuration reduces messes at the work site. In the preferred embodiment of the invention, the pump station is designed to be placed adjacent a five gallon-bucket filled with pre-mixed joint compound, such that the intake tube is located within the bucket and dips in the mixture of joint compound in the bucket. The legs for the pump station are located adjacent the bucket. The pump outlet preferably includes a quick-disconnect fitting, such as a cam lever coupling, in order to facilitate the connection and removal of various accessories such as filling tubes for application tools, filling adapters for flat boxes or corner angle finishing tools, a hose adapter for a rinsing and cleaning water hose, or a recirculation tube to direct joint compound from the pump outlet downward into the bucket.
The frame for the pump station is preferably constructed of two arch-shaped, steel members. The pneumatic pump is mounted to the arch-shaped members using a pair of mounting panels in such a manner that the pair of arch-shaped members provide four legs for the pump station, as well as looped handles above the pump. The leg portions of the arch-shaped members taper slightly outward in order to render the pump station stable as it stands on the ground (or as it is mounted to the top of a larger container or tub). The pneumatic pump is mounted substantially entirely within an imaginary peripheral surface contained within the arch-shaped members. The arch-shaped members, therefore, provide a protective cage that protects the pneumatic pump from damage when the pump station is laid on its side for transportation, or if the pump station tips over accidentally.
As mentioned, it is preferred that the pump station be designed so that the filling of tools occurs over the open top of the mud container (e.g., a five-gallon bucket). In order to accomplish this task with the joint compound application tool disclosed in Denkins et al., U.S. Pat. No. 5,863,146, a filling tube with a convoluted shape and a filling adapter at its end is removably connected to the quick-disconnect fitting at the pump outlet. A brace is provided between the front legs on the frame. The brace has a notch that supports the convoluted tube when the filling port for the application tool is inserted in the filling adapter for the convoluted filling tube. In addition, a removable mast is provided at the rear of the frame for the pump station. A support bar, preferably pivotable, is connected to the mast and supports the end of drywall application tool opposite the filling port. In this manner, the filling port is located above the open top of the mud container, and also the load on the frame remains relatively balanced while the application tool is being filled. In order to fill the mechanical tool disclosed in U.S. Pat. No. 2,815,142 a convoluted filling tube having a different configuration is used. The different configuration is needed for balancing purposes because the orientation of the filling port for the application tool is different than that disclosed in Denkins et al., U.S. Pat. No. 5,863,146. In the filling tube for the mechanical tool disclosed in U.S. Pat. No. 2,815,142, it is preferred that the location of the filling adapter on the convoluted filling tube be relatively low with respect to the pump station. Also, it is preferred that a cradle for the body of the application tool be permanently connected to the convoluted filling tube. When filling this type of mechanical tool (U.S. Pat. No. 2,815,142), it is not normally desirable to use the support brace on the mast.
Under normal operating conditions, it takes approximately 7 to 10 seconds to fill either the mechanical tool of U.S. Pat. No. 2,815,142 or the pneumatic tool of U.S. Pat. No. 5,863,146 using a pneumatic pump station designed in accordance with the invention. In order to control operation of the pump station, the preferred embodiment of the invention provides a control lever to operate a spring-actuated valve mechanism that supplies compressed air to the pneumatic pump. Also preferably, a guide member is provided for the control lever. The guide member provides a catch that holds the lever to maintain the spring-actuated valve in an open position, thereby rendering the pump in continuous operation. Continuous operation is most likely to be desirable when using the pump station for rinsing and cleaning, or even sometimes for recirculation of the drywall joint compound from the mud container (e.g. bucket or tub) through the pneumatic pump and back into the mud container (e.g. bucket or tub).
It should be apparent to those skilled in the art that the invention provides an easily portable, yet effective and versatile drywall joint compound pump station. For example, in its preferred embodiment, the pump station without attachment weighs approximately 25 pounds. In addition to being relatively light, the pump station in its preferred embodiment is stable and durable. Other advantages and features of the invention should be apparent to those skilled in the art upon reviewing the drawings and the following description thereof.